Hydraulic system for fire apparatus



April 17, 1956 E. J. ARPS 2,742,215

HYDRAULIC SYSTEM FOR FIRE APPARATUS 4 sheets-Shae: 1

Filed 00b. 15, 1952 & M/W J W5.

April 17, 1956 E. J. ARPS HYDRAULIC SYSTEM FOR FIRE APPARATUS 4 Sheets-Sheet 2 Filed 00*. 15, 1952 PF 64 F6 Z g w Ina/6 72507" Zfluzwzd all 57705 HYDRAULIC SYSTEM FOR FIRE APPARATUS Filed Oct. 15, 1952 4 Sheets-Sheet 3 April 17, 1956 E. J. ARPS 2,742,216

HYDRAULIC SYSTEM FOR FIRE APPARATUS Filed Oct. 15, 1952 v 4 Sheets-Sheet 4 2,742,216 HYDRAULIC SYSTEM FOR APPARATUS :Edmund J. A oshkosh, we, assiguor to Maxim .Motor Company, Middleboro, Mass, a corporation of Massachusetts V Application October 15, 1952, Serial No. 314,865

Claims. ((11.229-44) United States aw-m". Q"

Sometimes, a purely mechanical drive is employed to transmit the power from the take-0E to the tableand ladder while in other instances a combination of mechanical and hydraulic means. have been employed. Mechanical means involves the use of large gears and differential units which are bulky, hence taking. up a great deal of space where economy of space is highly desirable, are costly to manufacture and involve a .major dismantling operation if repair is required. l-lydrau'lic means, however, has many advantages over a minimum space and is, easy to repair. The chief disadvantage to employing hydraulic means is' that it is difficult to make and maintain a leakproof junction between; that part of the hydraulic system located on the chassis and thatpart carried by the turntable.

f :The principal objects of this invention are to provide I a hydraulic drive for the table and ladder Which will not require the use of flexible conduits, packed couplings, etc, which will be self contained and'compact, which will involve the minimum amount of mechanical connections between it and the power take-oil from the engine. and which itself will have certain novel aspects such as iliniitucontrol valves designed to make the operation safe in spite ofimproper or careless handling by .an

incompetent or inexpert operator.

As .herein illustrated a turntable is rotatably mounted on the chassis oftthe apparatus and supports an extension ladder which. normally occupies a horizontal position when not in use, the sections of which are normally detracted. ,The rotation of the table on the chassis, eleyation and depression of the ladder and extension and contraction thereof are all efiected hydraulically by a hydraulic pump driven by a take-ofi from theengine and the hydraulic system including the pump, conduits, valves and motor, are all located in a compact selfcontained unit on the table so as to turn therewith and so as to avoid the need for packed fluid couplings for any. part of the hydraulic system. .As herein illustrated a hydraulic pump .is mounted on the table at the center of rotation thereot'andis driven by a vertically arranged Islraft projecting upwardly. through the center or the mechanical means in that it can be designed to take up w table, the lower end of the shaft being connected by I retracting the sections of the ladder. In the "hydraulic 'llfnestn the hydraulic "cylinders there are metering valves for controlling the diow of flui-d in one direction and Patented Apr. 17, 1956 Withreference to the accompanying drawings wherein:

Fig. 1 is an isometric view of the turntable showing the hydraulic mechanism;

"Fig. 2 is a, diagrammatic layout of the hydraulic systemshowing the course of the hydraulic fluid vfor effecting rotation of the table;

Fig. 3 is a corresponding viewshowing the course of the hydraulic fluid for elevating and depressing the ladders;

Fig. 4 is a diagrammatic layout of the entire hydraulic systemshowing in addition to Figs. 2 and 3 the course of the fluid forextending and retracting the ladder sections Fig. 5 is a vertical diametrical sectionof the table longitudinally of the vehicle, showing the details of the table mounting;

' I Fig. 6 is an elevation of the table taken transversely of the vehicle showing the hydraulic motor, the ladder mountings and the control tower;

v Fig. 7 is an elevation of the hydraulic motor for efiectirig rotation of the table including the reduction gearing connecting themotor shaft to the table for eifecting rotation thereof, the ladder being shown in section; and,

Fig. 8 is an elevation of the hydraulic motor shown in Fig. '7 as viewed from theright hand side thereof.-

"Referring to the drawings, the turntable 10 is shown as of circular shape (Fig. 1) and as having a flat upper surface upon which is mounted for rotationwith the table the ladders L (Fig. 6) and hydraulic means. H including hydraulic elevating and extension cylinders 18 and '20 for elfccting elevation and extention thereof, a hydraulic pump 12 and a hydraulic motor 14 driven by the pump and connected to a gear reduction unit for effecting rotation of the table. The hydraulic fluid delivered by the pump 12 to the motor 14 and the elevating and extension cylinders 18 and Zil are controlled by a multiple selector valve assembly 17 (Figs. 1 and 4) mounted on the table, the individual valves of which are connected for selective operation to a control tower 22 (Fig. 6) also mounted on the table and movable there- 'with. The extending and retracting cylinder was shown in Fig. 6 is made fast to the ladder and is-movable in elevation and depression therewith. The table is supported for rotation on the chassis of the motor vehicle which is of customary construction having spacedparallel beams 24 (Fig. 5) running lengthwise of the vehicle, the beams being joined at their ends to form a rigid substantial rectangular frame. A frame 26 consisting of channel beams ismade fast to the chassis beams 24 .and forms a support for a ring 28 which is made fast thereto. The ring 28 has a series of teeth 30 (Figs. 5 and 7) formed 'in its peripheral surface for a purpose which-will appear "hereinafter and an inwardly projecting shoulder 32. A ring 34 is made fast to the underside of the table and has cut in its lower side right angle grooves. A corresponding ring 36 having a similar groove is bolted to the .ring 34 and in combination with the ring provides an annular. channel for receiving the lip 32. Ball bearings '40 are interposed between the shoulder 32 and the upper and lower rings 34 and 36 so that the .table will turn freely.

The hydraulic pump 12 (Figs. 1, 4 and 5) which supplies fluid under pressure to the various operating elements on thetable is located ,at the geometric center of the tablegso that its shaft 42 projects downwardly through 'theTtabIe. 'The shaft 42 is connected by acoupling 44 to a vertical shaft 46 also at the center of rotation of the table and this in turn is coupled by a sleeve 48 to "a shaft 50 extending vertically upward from a gea'r box 52 bolted to the underside of the frame 26 and which includes meshing gears not shown for changing rotational movement about a horizontal axis to rotational movement about a vertical axis, for example by way of a pinion and ring gear. Power is supplied to the gear box 52 by an articulated shaft 54 and clutch 56 to a gear 58 which in'turn meshes With a take off gear on the motor shaft. Thus by a direct drive vertically through the center of rotation of the table the fluid pump 12 may be driven regardless of the rotation of the table and without the necessity of having fluid conduits extending up through the table which require packing. This construction simplifies manufacture because it eliminates the large differentials customarily employed which take up a great dealof space and are costly. Moreover, it eliminates the danger of failure of hydraulic pressure since there are no connections running between a stationary part of the apparatus and the hydraulic system located on the turntable. No leakage of high pressure fluid will therefore go unnoticed by the operator, the entire hydraulic system and connections being located on the top of the table where they can be readily seen. v

The fluid supplied under pressure by the pump 12 to the various operating parts is drawn from a reservoir 60 (Figs. 4 and located at the underside of the table within the rings 34 and 36 and may be doughnut-shaped so as to surround the shaft 46. The reservoir is made fast to the table so that it turns with it, thus eliminating any fluid connection between the chassis and table. Referring to Fig. 4, the reservoir 60 is shown as connected by a conduit 62 to the pump 12 so that'the latter draws fluidfrom it and supplies it by way of a three-way coupling'64 and conduit 66 to the multiple selector valve 17. The valve 17 is of the spool type and has a core through which is a central passage through which oil furnished by the pump flows and is returned by way of a conduit 70 to the reservoir. In the event that all the valves are in neutral position fluid supplied by the pump 12 flows through the central passage of the selector valve directly to the reservoir. Sometimes during operations when one of the valve elements is open so as to divert fluid to one or the other of the operating elements excessive pressure may build up due to some interference of movement of parts and to avoid damage the relief valve 72 is provided which connects the three-way coupling 64 directly to the return by-pass conduit 74. Thus, when the pressure exceeds the setting of the relief valve 72 the fluid 'delivered by the pump 12 is allowed to by-pass the selector valve and to return to the reservoir directly through the conduit 74. 'The multiple selector valve 17 consists of a spool typecore and valve elements 76, 77 and 78 contained in the housing 68, the valve elements being independentlyoperable by levers 82, 84 and 86 respectively, thelatter being operable from a control tower 22 shown in Fig. 6 which has on it hand levers correspondingly numbered. Rotation of the table is effected by throw mg the control lever 86 forwardly or rearwardly to produce rotation in one direction or the other. Forward rotation of the lever 86 (Fig. 2) diverts fluid from the valve core 68 through the valve element 86 to a conduit 88 which is connected to one side of the hydraulic motor 14. A check valve 90 is interposed in this line. The

hydraulic motor in turn is connected by a shaft 92 to the gear reduction unit 16. Movement of the. control lever 86 in the opposite direction diverts fluid from the core 68 through "the valve element 86 to a conduit 96 and this in turn admits the fluid to the opposite side of the motor 14 by way of a check valve 98; thus it is evident that the motor 14 may be driven in either direction depending upon the position of the control lever 86 or may be held inoperative by placing the lever 86 in a neutral position. The return fluid in either case is conducted back from the reservoir by Way of the conduit 70.

Rotation of the table by way of the motor. 14 and gear reduction unit 16 is efiected as follows. The gear reduction unit 16 comprises a housing 94 (Figs. 7 and 8') containing reduction gearing not shown which connects the horizontally arranged shaft 92 entering the housing to a vertically arranged shaft 104 projecting from the bottom thereof through the table. The gear reduction unit is made fast to the table top by bolts 102 extending through a flange formed integral with the base of the unit. The shaft 104 is journaled in a sleeve 106 at the bottom of the unit which contains a suitable anti-friction bushing. The shaft 104 drives the table as follows. On the lower end of the shaft extended downwardly through a hole in the table there is made fast by means of a key a gear 110. A rigid gear housing 112 is bolted to the underside of the table to house this gear and others as will be described. Access may be had to the housing through a cover C bolted over an opening in its bottom. A bearing sleeve 114 is formed integral with the housing. The axis of the sleeve is vertical so as to be parallel to the shaft 104 and is lined with the bushing 116. The lower end of the shaft 118 is journaled in the' sleeve and its upper end is journaled in a bearing sleeve 122 lined with a bushing 124 which in turn is made fast to the'bottom of the gear reduction unit. The shaft is held in the journal for rotation by caps 126 and 128 fastened to its opposite end by bolts 130 and 132, the caps overlying the ends of the bearing sleeves. The shaft 118 is keyed to the gear 134 which meshes with the gear 110 and is ro tated thereby so as to effect rotation of the shaft 118. Also on the shaft 118 there is mounted a gear 136 which alternately may be made fast to the shaft so as to turn with it or allowed to turn freely on the shaft. The gear '136 is located directly below the gear 134. The underside of the gear 136 has a pair of diametrically arranged teeth 138 which may be interengaged with diametrically arranged slots formed in the upper surface of a collar 140 splined on the shaft 118 so as to rotate therewith but free to move longitudinally thereof. The collar has an annular groove 142 therein in which projects a pin 144 carried by a lever arm 146, the latter being fast to a horizontally arranged shaft 148 projecting through the wall of the housing which may be rotated by suitable means to raise or lower the collar 140 on the shaft and hence to engage or disengage the teeth 138 with the grooves in the'collar and as a result to lock the gear 136 to the shaft for rotation therewith or to permit it to rotate freely on the shaft. A stub shaft 150 is also made fast in a vertical position to the housing 112 and to this stub shaft there is fastened a gear 152'which meshes with the gear 136 and will be driven thereby when the gear 136 is locked to the shaft 118. An opening 154 is formed in one side of the housing 112 through which an arcuate portion of the gear 152 projects and meshes with the teeth 30 on the member 28 which as heretofore described and as shown in Fig. 5 is fast to the chassis. Rotation of the gear 152 will therefore cause it to travel about the periphery of the member 28 and hence turn the table about its vertical axis.

Thus it is evident that by throwing the control lever 86 in one direction or the other the table may be rotated in one direction or the other and by placing it in neutral the table may be locked in any given position.

Elevation and depression of the ladders which as shown in Figs. 1 and 6 are pivotally mounted at their lower ends on the table and as heretofore pointed out is elfected by a pair of hydraulic cylinders 18. As previously described fluid under pressure is delivered by the pump 12 to the selector valve spool 68 and if it is desirable to raise the ladders to an elevated position the control lever 82 (Fig. 3) is thrown forward to divert fluid from the spool to the valve element 76 and hence to admit fluid under pressure to a conduit 156. The conduit 156 is connected by a shut-elf valve 158 to branch conduits 160 and 162, these latter extending to the lower ends of the cylinders 18 by way. of check valves 164 and 166. As the fluid to the 'spoblfiS and thence throughihe return duct 70 to the reservoir '60. By "shifting the lever 2 in the opposite direction the fluid tak'e's an'oppos 'i'tecoui'ise, that is it passes through the conduit 174; valv =1'7 2',*brane'h passages E68 and 17i) ro theto en'dof in p" them downwardly while "the b'e pa sages '150 and1 62, valve 158 p valve housing and from thence thloughthe returnfluct #0 t theres'ervoir. is to be noted "that-the ehe'ck valves 1nd and 166 installed rat the 'lowe'r end of the cylinders "automatically prevent the fluid front being pushed out of the cylinders at an excessive rate so "that it is impossible for the ladder as it is being depressed to fall rapidly enough to damage "it. Moreover, if any of the'hydra ulic 'conduits should be-broken or otherwise rendered non-conductive of the fluid the ladderwill not fall but will descend at a safe rate." The check valves are, as arnatter or fact, adjustable so as to meter the fluid in apte'de'te'rrninedrate and it'hi'sris usu'ally setso "as to ive'a 'go'o'd factor of safety. As thus provided the ladder may be returned to its horizontal position b gravity the rate of descent being controlled solely by the check valves withoutthe use of'power. When lit tiesirahle to keep the ladder elevated for any length of'ri'me the shut-on'valve rss may be closed so as to hold the fluid pressure in the cylinder. The same result may be had by putting the lever 82 in neutral position, but this has the disadvantage of depending upon the fluid pressure in the system.

Extension and retraction in the ladder sections of which there are three is effected by a cylinder (Figs. 4 and 6) and control of the delivery of the hydraulic fluid to the cylinder is effected by the lever 84. Referring to the diagram Fig. 4, movement of the lever 84 in one direction will divert fluid from the spool through the valve element 77 and conduit 176 to the lower end of the cylinder 20 so as to raise the piston therein. The

fluid at the upper side of the piston is simultaneously exhausted through the conduit 184 and returns through the valve spool 168 and thence by way of return conduit 70 to the reservoir. Check valves 178 and 182 are inter- I posed in the lines 176 and 184 so as to prevent too rapid extension or retraction of the sections. A shut-oil valve 180 is also interposed in the line 176 so that the ladder sections may be locked in their extended positions rather than to depend upon the fluid pressure in the system when the lever is in neutral position. By throwing the lever 84 in the opposite direction fluid is delivered to the conduit 184 to the top side of the piston to force it downwardly and the fluid beneath it is exhausted through the conduit 176, returns to the selector valve and thence from the apparatus motor by a simple take oif as described above in the form of a vertical shaft extending through the center of rotation of the table. Moreover, the system is controlled and interlocked by shut-olf and check valves so that the parts cannot be damaged by admission of hydraulic fluid too fastthrough inexperience or careless operators. In fact, the control valves are so set that even if the levers are thrown to their full grenade extent the hydraulic fluid is metered ts-the operating parts at a rate which is consistent with proper operation. Moreover, should the table become blocked to rotation of the ladder to elevation or ext nsion so that an excessive pressure builds u the relief valves 72 will permit fluid to bypass the selector valve and return to the reservoir without damage to the operatin parts.

It -:should be understood that the present disclosure is for the purpose of illustration only and that this inven tion includes all modifications and equivalentswhich fall within the scope of the a pended claims;

1. In a fire ap aratus "a chassis, a power plant mounted thereon, a turntable, means supporting the turntable on the chassis for rotation thereon, said means having supportingco'ntact with the table intermediate its ce'nterand its perimeter and said-table having a central hole therein atiordi g a'cl'ear unobstructed assage from itsnndersid'e to its top side, hydraulically operated means for efiecting rotation of the table "in either direetion,- :said hydraulically operated means including means operable upon a art. of the table spaced radially of the center h'ole therein, a source of fluid pressure fast to the imiie'rside of the table, a pump for supplying fluid under pressure from said source to said hydraulically operated means, said pulr'lpbeing fastened to fthe table at'its center A of rotationfover the "hole or the table with its shaft extending down through the hole, a selector valve interposed between the pump and said hydraulically operated means for controlling the Zp'a'ssageof the hydraulic Build "to said hydraulicallyoperated means, said 'valvefbein' operable to admit fluid to one side or the other of said hydraulically operated means, said foregoing instrumentalities being located solely on the top of the table and movable therewith'in rotation so that there are'no fluid connections between the chassis and table and a mechanical coupling connecting the lower end of the pump shaft to the power plant beneath the table.

2. A fire apparatus according to claim 1 wherein the table is supported by an annular bearing concentric with the center of rotation of the table, a ring gear is fast to the chassis concentric-with the axis of rotation of the table, the hydraulically operated means includes a motor, motor shaft and gear train driven thereby, one gear in the train meshing with the ring gear and a clutch is interposed in the gear train for alternately making one of the gears fast or loose on its shaft in said train.

3. A fire apparatus according to claim 1 wherein a ring gear is fast to the chassis, a pinion is mounted on the table and meshes with the ring gear, and the hydraulic motor effects rotation of the pinion so as to travel around the ring gear.

4. A fire apparatus according to claim 1 wherein a ring gear is fast to the chassis, a pinion gear is mounted on the table so as to mesh with the ring gear and to travel thereabout upon rotation of the table and a gear reduction unit including a train of gears transmits power from the motor to the pinion.

S. A fire apparatus according to claim 1 wherein a ring gear is fast to the chassis, a pinion gear is mounted on the table so as to mesh with the ring gear and to travel thereabout upon rotation of the table, a gear train is interposed between the motor and pinion, the first gear in the train deriving rotation from the motor and the last gear in the train meshing with the pinion and means is interposed in the gear train for interrupting transmis sion of rotation through the gear train to the pinion.

6. A fire apparatus according to claim 1 wherein the pump shaft extends downwardly directly through the hole at the center of the table, a horizontal shaft is journaled on the chassis beneath the table and has a forward end of it connected to a take-0d from the power plant by way of a clutch and a converter is mounted on the chassis beneath the table connecting the rear end of the horizontal shaft to the lower end of the vertical shaft. for converting the horizontal rotation of the former .to vertical rotation of the latter.

z 7. A fire, apparatus according to claim 1 wherein a ring is fastened in a horizontal position to the chassis, said ring having a shoulder at its innerside and teeth at its outerside, a ring isfastened to the table having a groove at its outer side within which is seated the shoulder on the firstnarned ring, antifriction means is interposed betweenthe shoulder and the groove within which it is seated, a gear is mounted on the table and movable within the table about its. center of rotation, said last named gear being in mesh with the teeth on said first ring and means connects said last named gear to the hydraulic means on the table for effecting rotation thereof.

8. A fire apparatus according to claim 1 wherein the hydraulically operated means is a hydraulic motor, conduits connect opposite sides of the motor to the selector valve whereupon shifting the valve in one direction admits fluid to one side of the motor and shifting the valve inthe opposite direction admits fiuid to the opposite side of the motor.

9. A fire apparatus according to claim 1 wherein there .is an extension ladder pivotally mounted on the turntable for elevation and depression, a pair of hydraulic cylinders connected to the ladder, a system of fluid conduits con- .necting the pump to the cylinders including a selector valve, means for shifting the selector valve in opposite directions to admit fluid to one or the other and simul- 8 ofcylinders, limiting the discharge of fluid from their lower ends to a predetermined rate, and a shut-off valve in -;the; dis charge conduit operable to cut offreturn flow of thefiuid andhenceto lock the ladder in elevated posi- '10. A fire-apparatus according to claim ,1 wherein there is an extension ladder pivotally mounted on the turntablejor-elevation ,and depression, a hydraulic cylinder for extending and retracting the ladder sections, a system Oflfiuid'conduits connecting the pump to the hydraulic cylinder including a valve, means for alternately shifting the valve in opposite directions to admit fluid to one or the other and simultaneously exhausting fluid from the other or one end of the ends of the cylinder to extend or retract the ladder sections, and a metering valve inter- UNITED STATES PATENTS 835,153 Cooper Nov. 6, 1906 840,877 Steedman Jan. 8, 1907 983,212 Dahill Jan. 31, 1911 1,127,411 Dahill et al. Feb. 9, 1915 1,925,517 Bohlen Sept. 5, 1933 1,979,041 Luudskow Oct. 30, 1934 2,074,557 Pirsch Mar. 23, 1937 2,114,262 Havens Apr. 12, 1938 2,614,743 Arps Oct. 21, 1952 

